Lithium-ion batteries (LIBs), indispensable in modern life, owe their ubiquity to their high energy density, rechargeability, and optimal power performance. Among anode materials, graphite has remained the cornerstone of commercial LIBs for decades due to its stability and cost-effectiveness. Despite extensive efforts to identify superior alternatives with enhanced power and energy densities, graphite's dominance persists. However, during LIB operation, graphite reacts with electrolytes to form a structurally disordered solid-electrolyte interphase (SEI) layer. While this layer prevents undesirable side reactions, it also increases resistance, thereby limiting LIB performance.

In this study, we introduce a novel approach to address these challenges by functionalizing graphite edges using 4-bromo-benzoic acid via a direct Friedel–Crafts acylation reaction in a PPA/P2O5 medium. Furthermore, ionic liquid (IL) monomers were grafted onto the modified graphite surface to regulate SEI layer formation. This dual-functionalization strategy uniquely leverages the nonflammability, tunability, and wide electrochemical window of ILs to enhance anode performance.

Our findings reveal that IL-modified graphite significantly improves electrochemical cycle stability and durability, mitigating capacity degradation and resistance issues associated with conventional graphite anodes. This work offers a groundbreaking pathway to overcoming key limitations in LIB technology, advancing the development of next-generation energy storage systems.